With increasing functionality and capability of mobile devices, rich media content of high quality and value will also become available. Typically content such as applications or multimedia can be presented, executed or even be used to customize the end-user experience of a device and its applications.
With an expanding set of media formats, content can be combined into a single presentation e.g. using a video projector or be deployed simultaneously over multiple media interfaces such as audio, video and whiteboard in a video conference call.
It is also possible that more complex usage patterns will start to emerge and content be consumed in new ways e.g. using existing content rendering tools but with upgraded user interface (UI) hardware or the entire media stream be directed to an external device to render the content on a large display, projector, printing device, audio device, monitor, computer workstation or any other presentation device.
An external device could be any external device including rendering capabilities with a digital link to a mobile device for receiving content in a digital format and for rendering the content in a non-digital or analogue format, e.g. multimedia such as images, video, audio etc. Content can be defined as any data item in a digital format that can be rendered, i.e. transformed to and/or presented in a non-digital or analogue format.
For content protected with Digital Rights Management (DRM), this requires that the scope for where the content should be protected according to the DRM rules, hereinafter denoted as the DRM realm, need to be extended to devices with rendering capabilities external to a mobile device.
To securely provision and manage the distribution and usage of valuable content it is common to employ a DRM solution e.g. as defined by the OMA DRM standards, see e.g. OMA DRM v2. With DRM, the device implementation handling the presentation needs to be trusted and be certified to comply with a rule set defined by a DRM rights object, i.e. the collection of permissions and other attributes which are linked to protected content. Protected content can be described as digital work that is consumed according to a set of permissions in a rights object and wherein permissions are the actual usage or activity allowed over protected content.
DRM has two main objectives, to prevent unauthorized access to the content, and to control the usage of the content. These objectives are commonly defined to be valid to the point where the content is transformed from its digital representation to a non-digital or analogue representation, e.g. images on a screen, or music from a loud speaker etc.
In current implementations of DRM a DRM agent, the entity in the mobile device that manages permissions for protected content in the mobile device, i.e. the software entity implementing and controlling that the DRM rules are fulfilled, and Rendering Servers, i.e. the software entities transforming the digital representation to a non-digital or analogue format, are implemented as one integral part in view of its physical design, as well as its software control system.
Therefore, the DRM realm needs to be extended to also include external devices comprising rendering servers and thereby rendering capabilities, hereinafter denoted as external rendering servers, which are not part of the same physical device, or software control system, as the entity where the DRM agent resides, e.g. an entity such as a mobile device such as a mobile telephone or communicator i.e. electronic organizer, smart phone, personal digital assistant (PDA), handheld computer etc. The mobile device can be described as an entity, hardware/software or a combination thereof, within a user equipment that implements a DRM agent.
As existing DRM solutions only work end-to-end, assuming a mobile device is the final end point, there is consequently no provisioning for the fact that the mobile device could be upgraded with new hardware (not from the original device manufacturer) or the DRM protected content being exposed in an un-protected manor while being in transit between a mobile device and an external device, such as a presentation device.
There is also nothing that prevents an adversary peripheral device to expose itself as e.g. a harmless printing device while hiding an elaborate solution for reverse engineering content into a content format that could be redistributed strictly against the intention of the DRM protected realm.
US 2004/0158712 discloses a system and method for managing non-free multimedia contents in an intranet. The system includes proxy managers provided in a server of the intranet, for example, a media center or set-top box, and clients, for example, DRM smart clients in wired/wireless digital information appliances, such as Digital TVs or PDAs. Various kinds of encrypted multimedia contents and license information are converted by the proxy managers into multimedia contents and license information having a format executable by the DRM smart clients.
Even though the above prior art method provides a method for managing non-free multimedia content in an intranet, the above method still requires the appliances to include DRM smart clients. Hence, since the above method still requires the appliances to include DRM smart clients, a high DRM complexity is yielded in the appliances. Therefore, it remains a problem to provide a method for rendering content on an external device with limited DRM complexity and capabilities such as a printing device or a video projector that solves the above problems.
In particular, application of the above prior art method would require the proxy manager to receive both protected content and license information from a content provider which it converts and transfers to the client and wherein the client subsequently validates the license information requiring a DRM agent in the client. Furthermore, the above prior art method discloses that no license validation is performed before the content is further converted and transferred to the client.
It is a problem of the above prior art system that the complexity is inevitably increased by the extension of the DRM realm, more specifically the complexity is increased by the need to obtain information regarding e.g. license credentials/information and/or permissions associated to the content and/or which particular DRM scheme that is used in the mobile device, and further the complexity is also increased by the DRM functionality which is required in the external device.